Real world evidence of systemic therapy in hormone receptor positive advanced breast cancer (HR+ ABC) in Australia: ARORA Registry.
Authors: Sheau Wen Lok, Iris Tung, Angelyn Anton, Sally E. Baron-Hay, Richard H. De Boer, Frances M. Boyle, Ian M. Collins, Katharine Cuff, Lucy Gately, Chloe L. Georgiou, Sally Greenberg, Bhaskar Karki, Louise M. Nott, Michelle K. Nottage, Natalie Rainey, Javier Torres, Belinda Jane Yeo, Peter Gibbs, Vanessa Wong
Journal: Journal of Clinical Oncology (2023)

e13054 Background: The last decade has seen a rapid increase in systemic treatment options for patients with HR+ ABC. The incorporation of CDK4/6 inhibitors in first line (1L) is now standard practice leading to improved survival. However, there is a paucity of data on uptake of standard therapies and associated toxicities in the real-world setting. Methods: ARORA is a secondary data use study of Australian patients with HR+ ABC capturing prospective data on patient characteristics, systemic therapy sequencing and treatment outcomes in routine clinical practice. Patients aged &gt; 18 diagnosed after 1 Jan 2020 are eligible. Results: Data from 294 patients at 16 sites was analysed with a median follow up of 15 months. Mean age was 63 years; 23% &gt; 75 years. 64% were ECOG 0, 5.4% had a familial syndrome, 61% had relapsed metastatic disease and 19.4% had bone only metastases at diagnosis. Of patients who relapsed, 14.6% and 52.8% received neoadjuvant and adjuvant chemotherapy respectively, and 77.5% received adjuvant endocrine therapy (ET). 41% relapsed on or within 12 months of stopping adjuvant ET. 5 patients (1.7%) did not receive any systemic therapy for ABC. Of those on 1L therapy, 223 (77%) received CDK4/6i + ET, 38 (13.1%) received ET alone and 26 (9%) received chemotherapy. Choice of 1L CDK4/6i was palbociclib (50.7%), ribociclib (34.5%) and abemaciclib (9.9%). Patients who received 1L ET alone were older (mean age 75 vs 62 years; 68.4 vs 16.6% &gt; 75 years) with poorer performance status (34.2 vs 6.3% ECOG ≥2) and more comorbidities (76.3 vs 36.8% Charlson index &gt; 2) compared to those who received 1L CDK4/6i + ET. Conversely, those on 1L chemotherapy were younger (mean age 54, 96.2% &lt; 75years), with better performance status (69.2% ECOG 0-1) and fewer comorbidities (88.5% Charlson index &lt; 2). Patients receiving 1L chemotherapy were more likely to have visceral metastases compared to those on CDK4/6i + ET (69.2 vs 43.1%, p = 0.01). The most common reported toxicities in patients receiving CDK4/6i were diarrhea (59% abemaciclib vs 3.9% ribociclib vs 2.7% palbociclib), neutropenia (38.1% palbociclib vs 32.5% ribociclib vs 22.7% abemaciclib) and nausea/vomiting (27.3% abemaciclib vs 22.1% ribociclib vs 12.4% palbociclib). Abnormal LFTs occurred in 9.1% of patients on abemaciclib (vs 3.9% ribociclib and &lt; 1% palbociclib). 2 patients (1.8%) on palbociclib had pneumonitis whilst 1 (1.3%) on ribociclib had QTc prolongation. Survival data is immature. Conclusions: Despite CDK4/6i + ET being gold standard treatment in 1L HR+ ABC, only 3/4 of patients received this combination, with a substantial minority receiving ET alone or chemotherapy. Age, ECOG status, comorbidity burden and presence of visceral disease appear to be major determinants of treatment choice. Toxicity profile of the CDK4/6i agents were mostly in line with clinical trial results, although longer follow up is needed to confirm this.